The teachings of the present invention are particularly applicable to the art of gripper feed mechanisms. However, in its broader aspects, the present invention can be applied to any type of mechanical device in which it is desired to adjust cam- or eccentric-type devices used for timing or generating reciprocating motion.
Feeds of various sorts are used to provide an automated advancement of work material to a work station such as a punch press. One type of feed mechanism that has been used in the past for strip material is the gripper feed, which employs one or more reciprocating grippers to advance the sheet material. With advances in technology, many types of gripper-feed designs have fallen into disfavor; in addition to their speed limitations, gripper feeds have suffered from the fact that, due to the method of driving the strip-feed mechanism, access to the position where adjustment of stroke length can be performed is somewhat difficult. It is accordingly an object of the present invention to provide easy access to the point of adjustment of feed stroke.
Another shortcoming in some prior-art gripper feeds involves the elaborate mechanisms previously employed to permit adjustment of feed stroke. The reciprocating motion in the gripper-type feeder is often provided through the use of an eccentric member rotated by the main drive. In order to adjust the stroke, either the eccentricity of the eccentric member or the mechanical advantage provided by a particular link would typically have to be modified. However, at least in the case of an adjustment of eccentricity, the mechanisms that have been employed to permit the adjustment are somewhat elaborate. Accordingly, it is another object of the present invention to reduce the complexity of the adjustable eccentric mechanism. In its broader aspects, these teachings are applicable not only to the gripper-feed mechanism but also to various other types of devices in which an eccentric- or cam-type timing or drive mechanism is employed.